There's also sorts of useful data and statistics at "Chuck Wood's Moon: Compendium of Lunar Science and History" at http://www.lpod.org/cwm/DataStuff/Data.htm

NASA has a website called "Basics of Space Flight", http://www.jpl.nasa.gov/basics/ which began life as a training document for NASA engineers, but which they quickly realised had much wider appeal. An excellent site to start exploring from.

"The Slingshot Effect" by Bob Johnson has a very thorough discussion of gravity assist techniques: http://www.dur.ac.uk/bob.johnson/SL/

NASA has a movie explaining the aerobraking technique which was used to get Mars Global Surveyor and Mars Reconnaissance Orbiter into orbit: http://mars.jpl.nasa.gov/gallery/video/movies/aerobraking.mov Sources for images used:

Background image: View of the lunar surface taken from Apollo 8, looking southward from high altitude across the Southern Sea. NASA Photo ID: AS08-12-2192. http://images.jsc.nasa.gov

Deep Impact transit movie: from NASA Mission News http://www.nasa.gov/topics/solarsystem/features/epoxi_transit.html

Lunar libration: Antonio Cidadao's Lunar and Planetary Observation and CCD imaging http://www.astrosurf.com/cidadao/animations.htm

Moon's orbit: redrawn from "The Once and Future Moon" by Paul Spudis, figs 1.5 and 1.6

Moon at perigee and apogee: from "Inconstant Moon The Moon at Perigee and Apogee" by John Walker http://www.fourmilab.ch/earthview/moon_ap_per.html

Microcrater: from A MEETING WITH THE UNIVERSE: Science Discoveries from the Space Program http://www.hq.nasa.gov/office/pao/History/EP-177/cover.html, Appendix A-1

King crater: from APOLLO OVER THE MOON: A VIEW FROM ORBIT http://www.hq.nasa.gov/office/pao/History/SP-362/cover.htm, fig. 149

Gagarin crater field: from http://www.hq.nasa.gov/office/pao/History/SP-362/cover.htm">APOLLO OVER THE MOON: A VIEW FROM ORBIT, fig. 97

Young craters: the young impact crater Linne, taken by Apollo 15. From http://www.hq.nasa.gov/office/pao/History/SP-362/cover.htm">APOLLO OVER THE MOON: A VIEW FROM ORBIT, fig. 102

Euler crater: taken by Apollo 17. From http://www.hq.nasa.gov/office/pao/History/SP-362/cover.htm">APOLLO OVER THE MOON: A VIEW FROM ORBIT, fig. 138

Tycho: from the Consolidated Lunar Atlas http://www.lpi.usra.edu/research/cla/menu.html

Orientale: taken Lunar Orbiter 5, http://nssdc.gsfc.nasa.gov/planetary/lunar/lunarorb.html

Galileo image of Orientale: from the Galileo Legacy Site, http://galileo.jpl.nasa.gov/gallery/earthmoon-moon.cfm

Basins: from a talk by Hal Levison, "Review of Dynamic Models Associated with Late Heavy Bombardment", http://www.boulder.swri.edu/~hal/talks/nice/Bomb/basins.html

Lunar topography: from Araki et al, 2009, "Lunar global shape and polar topography derived from Kaguya-LALT laser altimetry", Science 323 897

South Pole-Aitken: Clementine image, from NASA's Solar System Exploration Gallery, http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=802

Old and young craters: from "Craters and Planetary History" by Steven Dutch, http://www.uwgb.edu/dutchs/planets/crathist.htm

Crater size distribution: from "Introduction to Cratering Studies" by Greg Herres and William Hartmann, http://www.psi.edu/projects/mgs/cratering.html

Pre-space flight depictions of the lunar surface: from a 1955 book "Exploring the Moon" by Roy Gallant, illustrated by Lowell Hess. From "Dreams of Space" by John Sisson http://sun3.lib.uci.edu/~jsisson/john.htm

Lunar surface: AS17-137-21011, from http://images.jsc.nasa.gov/iams/html/pao/as17.htm

Late heavy bombardment: from "Impact Processes on the Early Earth" by Christian Koeberl, Elements, vol 2 p. 211-216 (2006)

Maria: from an essay on The Grand Canyon and the Moon by Charles R. Cowley http://www.astro.lsa.umich.edu/users/cowley/

Rotating moon, moon interior: from Views of the Solar System by Calvin J. Hamilton http://www.solarviews.com/eng/moon.htm

Hadley Rille: http://www.nasm.si.edu/collections/imagery/apollo/AS15/a15landsite.htm and NSSDC Image Catalog: Apollo 15 http://nssdc.gsfc.nasa.gov/imgcat/html/mission_page/EM_Apollo_15_page1.html

Lichtenberg crater: Photo Number IV-170-H1, Digital Lunar Orbiter Photographic Atlas of the Moon http://www.lpi.usra.edu/research/lunar_orbiter/index.html

Radar image of moon: from Cornell University: Chronicle Online http://www.news.cornell.edu/stories/Oct06/campbell.lunarice.html

Throwing balls into orbit: redrawn from "To Rise from Earth" by Wayne Lee, Fig. 1

Image of Earth: from Visible Earth: The Blue Marble, http://veimages.gsfc.nasa.gov/2429/globe_east_540.jpg

All the orbit figures are redrawn from "To Rise from Earth" by Wayne Lee, animated by HMJ

Mars image: HST pictures of Mars at opposition, taken on February 25, 1995. Image STScI-PRC1995-17a, from the Hubble Space Telescope News Center archive, http://hubblesite.org/newscenter/

Aerobraking: from Mars Reconnaissance Orbiter press release 25 August 2006, http://mars.jpl.nasa.gov/mro/newsroom/pressreleases/20060825a.html and Mars Global Surveyor MAG/ER http://mgs-mager.gsfc.nasa.gov/overview/aerobraking.html

Aerobraking animation: extracted from NASA's Mars Exploration Program: Videos http://mars.jpl.nasa.gov/gallery/video/movies/aerobraking.mov

Jupiter image: from StarDate Online http://stardate.org/resources/ssguide/jupiter.html

Slingshot diagram: redrawn from "The Slingshot Effect" by Bob Johnson http://www.dur.ac.uk/bob.johnson/SL/

Galileo's VEEGA trajectory: from http://www2.jpl.nasa.gov/galileo/sepo/education/bulletin/launch_to_g29.html

Mercury trajectory: from http://www.mercurytoday.com/messenger/missiondesign.html

SMART-1 ion engine: from SMART-1: The magic of ion engines, http://www.esa.int/SPECIALS/SMART-1/SEMLB6XO4HD_0.html